Programming Languages Research Group: Git - pingpong.git/blob

   1 package edu.uci.iotproject.analysis;
   2
   3 import edu.uci.iotproject.io.PcapHandleReader;
   4 import org.pcap4j.core.*;
   5
   6 import java.time.Instant;
   7 import java.util.Collections;
   8 import java.util.List;
   9 import java.util.concurrent.TimeoutException;
  10
  11 /**
  12  * TODO add class documentation.
  13  *
  14  * @author Janus Varmarken
  15  */
  16 public class TriggerTrafficExtractor implements PcapPacketFilter {
  17
  18     private final String mPcapFilePath;
  19     private final List<Instant> mTriggerTimes;
  20     private final String mDeviceIp;
  21
  22     private int mTriggerIndex = 0;
  23
  24
  25     private static final int INCLUSION_WINDOW_MILLIS = 20_000;
  26
  27     public TriggerTrafficExtractor(String pcapFilePath, List<Instant> triggerTimes, String deviceIp) throws PcapNativeException, NotOpenException {
  28         mPcapFilePath = pcapFilePath;
  29         // Ensure that trigger times are sorted in ascending as we rely on this fact in the logic that works out if a
  30         // packet is related to a trigger.
  31         Collections.sort(triggerTimes, (i1, i2) -> {
  32             if (i1.isBefore(i2)) return -1;
  33             else if (i2.isBefore(i1)) return 1;
  34             else return 0;
  35         });
  36         mTriggerTimes = Collections.unmodifiableList(triggerTimes);
  37         mDeviceIp = deviceIp;
  38     }
  39
  40
  41     public void performExtraction(PacketListener... extractedPacketsConsumers) throws PcapNativeException, NotOpenException, TimeoutException {
  42         PcapHandle handle;
  43         try {
  44             handle = Pcaps.openOffline(mPcapFilePath, PcapHandle.TimestampPrecision.NANO);
  45         } catch (PcapNativeException pne) {
  46             handle = Pcaps.openOffline(mPcapFilePath);
  47         }
  48         // Use the native support for BPF to immediately filter irrelevant traffic.
  49         handle.setFilter("ip host " + mDeviceIp, BpfProgram.BpfCompileMode.OPTIMIZE);
  50         PcapHandleReader pcapReader = new PcapHandleReader(handle, this, extractedPacketsConsumers);
  51         pcapReader.readFromHandle();
  52         // Reset trigger index (in case client code chooses to rerun the extraction)
  53         mTriggerIndex = 0;
  54     }
  55
  56     @Override
  57     public boolean shouldIncludePacket(PcapPacket packet) {
  58         // New version. Simpler, but slower: the later a packet arrives, the more elements of mTriggerTimes will need to
  59         // be traversed.
  60         return mTriggerTimes.stream().anyMatch(
  61                 trigger -> trigger.isBefore(packet.getTimestamp()) &&
  62                         packet.getTimestamp().isBefore(trigger.plusMillis(INCLUSION_WINDOW_MILLIS))
  63         );
  64
  65         /*
  66         // Old version. Faster, but more complex - is it correct?
  67         if (mTriggerIndex >= mTriggerTimes.size()) {
  68             // Don't include packet if we've exhausted the list of trigger times.
  69             return false;
  70         }
  71
  72         // TODO hmm, is this correct?
  73         Instant trigger = mTriggerTimes.get(mTriggerIndex);
  74         if (trigger.isBefore(packet.getTimestamp()) &&
  75                 packet.getTimestamp().isBefore(trigger.plusMillis(INCLUSION_WINDOW_MILLIS))) {
  76             // Packet lies within INCLUSION_WINDOW_MILLIS after currently considered trigger, include it.
  77             return true;
  78         } else {
  79             if (!trigger.isBefore(packet.getTimestamp())) {
  80                 // Packet is before currently considered trigger, so it shouldn't be included
  81                 return false;
  82             } else {
  83                 // Packet is >= INCLUSION_WINDOW_MILLIS after currently considered trigger.
  84                 // Proceed to next trigger to see if it lies in range of that.
  85                 // Note that there's an assumption here that no two trigger intervals don't overlap!
  86                 mTriggerIndex++;
  87                 return shouldIncludePacket(packet);
  88             }
  89         }
  90         */
  91     }
  92
  93 }